Short communication: HIV type 1 tropism determination in a novel dried blood spot membrane and the use of a mixture of outer nested polymerase chain reaction primers.

Genotropism was determined in 608 Brazilian samples collected in dried blood spots using Polyethersulfone collection cards. Patients were infected by subtype B (88.8%), F (5.6%), C (3.3%), A (1.8%), and G (0.5%). All patients were exposed to three classes of antiretrovirals, and 59.8% of the samples harbored R5 viruses, 35% non-R5-tropic viruses, and 5.1% harbored mixtures of R5 and non-R5-tropic viruses, with non-R5 more prevalent among clade B-infected patients as compared to non-B (42.8% versus 19.1%; p<0.0003). A strategy using a mixture of outer nested polymerase chain reaction (PCR) primers reduced the number of negative PCR results from 39% to 19%.

The use of real-time PCR to detect hepatitis C virus RNA in dried blood spots from Brazilian patients infected chronically.

Collecting and transporting samples for RNA analysis can be challenging, especially in situations where financial resources are limited. In this study, a quantitative real-time PCR (qPCR) for the analysis of HCV RNA was developed and adapted for use with dried blood spot (DBS) samples. A qPCR for HCV 5'NCR, an internal control and a calibration curve were developed, and the sensitivity, specificity and dynamic range of amplification were evaluated using a panel of viruses. Plasma and DBS samples from 100 patients who had completed four weeks of Peginterferon alfa-2b+Ribavirin treatment were collected (DBS on SS903 collection cards and transported at room temperature). After 24 weeks of treatment, samples were collected from 68 of these patients. Of the 168 samples, 2 yielded false-negative results, and 4 yielded false-positive results (sensitivity was 98%, specificity was 94.3%, positive predictive value was 96.1%, and negative predictive value was 96.9%). Additionally, 2039 DBS samples from 1114 patients currently undergoing treatment for a chronic HCV infection in a clinical trial were tested. Only 10 samples out of the 2039 yielded invalid results warranting re-collection of DBS. The detection of HCV RNA in DBS can be a cost-effective strategy for HCV treatment monitoring, especially in settings where resources are limited.